The objective of the experiments described in this proposal is to: 1) determine if there is a difference in the frequency of transcription of DNA sequences coding for mRNA and those coding for nuclear restricted non-messenger RNA. 2) examine the dynamics of the processing (degradation and export to cytoplasm) of messenger and non-messenger nuclear RNA sequences. 3) Establish whether there is a relationship between DNase I sensitivity of DNA sequences in nuclei and their transcriptional activity. These experiments will be carried out using HeLa cells as the experimental system. The general approach will be to purify 3H-labeled non-repetitive DNA sequences which are complementary to mRNA and non-messenger hnRNA sequences. These 3H-labeled probes will be hybridized to an excess of 32P pulse-labeled hnRNA. The concentration of the probes in nuclear RNA, as determined by their kinetics of hybridization, and the specific activity of the hybridizing RNA sequences, will allow conclusions to be drawn regarding the relative frequency of transcription of the messenger and non-messenger sequences. It will also be possible to draw conclusions regarding the relative rates at which the two sets of sequences are removed from the nucleus.